The field of the present invention is calculators that attach to an article disposed on the user of the calculator.
People who use calculators often need their hands free when they perform tasks other than mathematical calculations. Calculator holders have been invented to meet this need. U.S. Pat. No. 4,801,059 to Hayes discloses such a device. Such holders require a substantial amount of material apart from the calculator itself. They therefore require elaborate means for attachment to a belt or some other article on the user's person. The holder is also typically difficult to attach to and detach from the aforementioned article. Finally, the calculator must be detached from the holder before the calculator can be used because the display would be upside down when attached to a persons belt.
Calculators embedded in watches have also been created. While watch calculators permit the user to carry the calculator with hands free, watch calculators are inconvenient and inefficient to use because the input elements are small and time-consuming to activate. In addition, watch calculators are not easily detached from the watch's band or strap.
A calculator with an integral means of selective attachment to an external article on the user's person, such as a belt, key ring or key chain, has been invented. U.S. Pat. No. D502,497 issued to Tien discloses such a calculator. However, this device does not allow comfortable use of the calculator while attached to the user.
There is thus a need for a calculator which can be readily attached to a user without a separate holder and can be used while attached so that the user can efficiently move from one place to another with hands free during repeated use of the calculator.